1. Field of the Invention
This invention generally relates to an electronic device, and more particularly to a leadless semiconductor chip package and a manufacturing method thereof, wherein a semiconductor die is encapsulated by a plastic package body in a manner that the backside surface of the die is exposed through the plastic package body.
2. Description of the Related Art
FIG. 1 depicts a conventional semiconductor chip package including a lead frame for supporting a semiconductor die 100. The lead frame includes a plurality of leads having outer lead portions 106 and inner ends 107. The die 100 is attached onto a die pad 111 by means of a silver paste 114. The die pad 111 is connected to the lead frame by several supporting bars (not shown in FIG. 1). The outer lead portions 106 are used for electrical coupling to an outside circuit. The die 100 has bonding pads 117 electrically interconnected to the inner ends 107 of the lead frame though bonding wires 115. The die 100, the die pad 111, the inner ends 107 of the lead frame and bonding wires 115 are encapsulated in a plastic package body 116 made of insulating material such as epoxy.
Because the plastic package body 116 completely surrounds the die 100, the heat generated from the die 100 during normal operation must pass through the package body 116 to outside. Due to the insulating properties of the package body 116, heat dissipation from the die 100 is resisted, thereby creating, in some instances, high temperatures within the conventional package which might impair or damage the die 100.
Therefore, the semiconductor industry develops a leadless semiconductor chip package 200 (as shown in FIG. 2) mainly comprising a die 210 disposed on a die pad 220 of a lead fame. The lead frame comprises a plurality of leads 230 electrically connected to the die 210 through a plurality of gold wires 240. The die and the lead frame are enclosed in a package body 250 wherein the lower surface of the lead frame is exposed through the package body 250. Consequently, the heat generated from the semiconductor die during normal operation can be directly transferred through the die pad 220 of the lead frame to outside thereby enhancing the thermal performance of the leadless semiconductor chip package 200. However, since the lower surface of the lead frame is exposed through the package body, flash problems tend to occur at the edge 220a of the die pad 220 and the edge 230a of the leads 230, which may be fatal to the solder joint reliability thereof.